The present invention relates to a method of assembling cutting inserts on a milling cutter body, and to a milling cutter body on which the inserts have been assembled.
In milling cutter tools having detachably clamped cutting inserts, it has often turned out to be difficult to position the inserts with the required precision for ensuring that a good surface smoothness on the workpiece is achieved, and for ensuring a long tool life. In order to attain the required surface smoothness, it is required that the cutting inserts attain the most exact position as possible, in particular in the axial direction, i.e., parallel to the axis of rotation of the tool. If the axial positioning is unsatisfactory, then an axial play arises, which results in a deteriorated surface smoothness. On the other hand, tests have shown that the best surfaces are obtained if the surface is generated by only one of the inserts which protrudes axially forwardly beyond the other inserts.
For commercially available milling cutters, the axial play, i.e., the maximum axial distance between the operative parallel land cutting edges of two individual inserts, may for instance be around 30 .mu.m. However, since the size of this play is purely random, more than one cutting insert may protrude axially relative to other cutting edges. If then two protruding cutting inserts become located circumferentially one after the other in the milling cutter body, there is a risk that the second cutting insert will not cut a proper chip, but instead will only scratch the surface in an undesired way.
The milling cutter bodies of today are usually constructed with a positive axial angle and a negative radial angle. A representative example of this arrangement is shown in Pantzar U.S. Pat. No. 5,199,827, which is hereby incorporated by reference. This has been found to result in a favorable chip breaking due to the fact that the chips are directed outwards, away from the milling cutter body, and upwards, away from the workpiece. Over the years, this positive/negative basic geometry has established its position as generally the most useful.
Thus, a primary object of the present invention is to enable an improved workpiece surface to be obtained by means of milling cutter bodies having said positive/negative basic geometry.
A further object of the present invention is to improve the surface on the workpiece independently of the radial angle of the cutting inserts.
Still another object is to provide a simple way of positioning one of the cutting inserts in the milling cutter body axially forwardly of the others.